The Efficiency of Segmental Le Fort I Surgery in Clear Aligner Therapy of Skeletal Class III Deformity: A Pilot Study

Introduction:<bold> </bold>The purpose of this study was to investigate the efficiency of segmental Le Fort I osteotomy in clear aligner therapy of skeletal Class III deformities and to explore whether Le Fort I segmental osteotomy was effective for maxillary incisor axis correction and reduced the duration of perioperative orthodontics. Materials and methods:<bold> </bold>Patients who had skeletal Class III deformities (ANB<0) treated with extraction of the maxillary first premolars, segmental Le Fort I osteotomy, and clear aligners therapy were included in this retrospective study. We measured the amount of tooth extraction space that was closed by surgery and recorded the preoperative orthodontic and total treatment duration. Lateral cephalograms were analyzed to measure changes of maxillary incisor inclination before treatment (T0), 1 week before surgery (T1), 1 week after surgery (T2), and after total orthodontic treatment (T3). Statistical analyses were performed, and the P value was set at 0.05. Results:<bold> </bold>The sample was composed of 15 patients aged 19 to 30 (M=22.9) years. The average preoperative orthodontic treatment duration was 16.2 +/- 5.22 mo, with 33.5 pairs of clear aligners. The gap at the extraction site decreased from 5.42 +/- 1.57 mm to 0.80 +/- 0.62 mm on average after surgery. U1-SN and U1-NA(deg) increased sparingly with preoperative decompensation, decreased in quantity after surgery, and then slightly increased with postoperative compensation (T2<T3<T0<T1; triangle U1-SN, triangle U1-NA: T1-T2, P <0.05; T0 - T1 and T2-T3, P >0.05). Conclusions:<bold> </bold>Le Fort I segmental osteotomy assisted decompensation of the upper anterior teeth and reduced the duration of preoperative orthodontics with clear aligners.